Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$241.82	8.621%	$262.6673	$262.67	$262.65	$262.70
Purchase #2	$105.29	10.415%	$116.256	$116.26	$116.25	$116.30
Purchase #3	$31.93	4.593%	$33.3965	$33.40	$33.40	$33.40
Purchase #4	$182.97	3.377%	$189.1489	$189.15	$189.15	$189.10
Purchase #5	$107.45	11.276%	$119.5661	$119.57	$119.55	$119.60
Purchase #6	$135.87	4.139%	$141.4937	$141.49	$141.50	$141.50
Purchase #7	$127.80	9.129%	$139.4669	$139.47	$139.45	$139.50
7 purchase totals =	$933.13		$1,001.9954	$1,002.01	$1,001.95	$1,002.10